FreeImage.h Patch for iOS / OSX

Fix for FreeImage error when compiling on OSX for iOS (Xcode)

Problem:
"error: typedef redefinition with different types ('signed char' vs
'int32_t' (aka 'int'))
typedef signed char BOOL; "

Solution:
Use #define and #undef instead of typedef for the type definitions.

Updated for the new version of FreeType and to support the new 64bit
data structures with the define/undef.
Based on the changes @ofTheo made 3 years ago to the same file
#76
FreeImage.h Fixes for IOS - BOOL rename to FREEIMAGE_BOOL
Merge pull request #1889 from danoli3/master

Fix for FreeImage.h typedef problems for OSX/iOS Xcode